Process of separating and recovering constituents of waste liquor from the soda and sulphate processing of coniferous woods



Feb. 19,' 1946. OVAS ET AL 2,395,284 PROCESS OF SEPARATING AND REOOVERING CONSTITUENTS OF WASTE LIQUOR FROM THE SODA AND SULPHATE PROCESSING OF CONIFEROUS WOODS Filed Aug. l, 1942 200% MEM/NdA /6//7 /V/LAB/ETAPE Prr- P/m/ Wim .55m/M9 A 720i/V216 VE TORS including sterols.

- UNITED sTATEs PATENT OFFICE PROCESS F SEPARATING AND RECOVER- ING CONSTITUENTS vOli' WASTE LIQUOR FROM THE SODA AND SULPHATE PROC- ESSING OF CONIFEROUS WOODS Joseph John Lovas, Ridgewood, and Paul F.

` Bruins, Douglaston, N. Y.

Application August 1, 1942, Serial No. 153,292 8 Claims. (Cl. 260-97.5)

This invention relates to a new and economical process of separating an organic mixture containing ne or more Itypes of rosin acids, fatty acids, sterols, and other unsaponiiiable organic material, with particular reference to tall oil.

for in place of methyl Dropyl, butyl or any higher monohydric alcohol. For the ketone solvent, we may use methyl ethyl ketone, diethyl ketone, or any aliphatic ketone Tall oil is obtained as a by-product in the socalled sulphate process of manufacturing kraft paper. Thetall oil is recovered from the waste liquors as the sodium salts of the fatty and rosin acids emulsiiled with unsaponiiiable oil"m'atter When the spent black liquor obtained from the cooking of southern pine wood chips is concentrated, the emulsion floats to the surface as a dense foam or paste. Talloil is recovered by skimming oil and hydrolyzing the foam with mineral acid.

We have found that this crude tall oil is a mixture of more than one rosin acid, several types of fatty acids, sitosterols, higher alcohols and hydrocarbons. To be more specific, we vhave separated a sample of tall oil into the following constituents:

l Per cent Fatty acids 45.00

\ Crystalline abletic acid 25,00

Rosin acids (structure unknown) 15.00 Sitosterols 1.35 Higher alcohols and hydrocarbons 10.00 Unidentified residue 3. 6,5

The proportions of the constituents vary in different samples of tall oil due to its source or method of initial treatment.

In our process we employ the esteriiication,

principle in making a separation of the components of tall oil by esterifying with a monohydric alcohol in the presence of a catalyst. After esteriiication of the fatty acids, an organic solvent Which when substantially anhydrous is completely miscible with a hydrocarbon, is added. This solvent must have the property of not being a solvent for either sodium abietate. or the sof that these solvents are cheap and abundant. We do not wish to limit ourselves to these solvents,

having an aiiinity for water. We may employ gasoline or kerosene and the like in place of hexane.

Generally, our process is as follows:

The crude soaps that are skimmed from the black liquormay be washed by dissolving in water and salting out with brine. The soap, purified, or as initially recovered, is then hydrolyzed by means of a mineral acid such vas sulphuric acid.

A The crude tall oil is decanted and heated. After this heat treatment, it is esteriiied with methyl alcohol (anhydrous) using concentrated sulphuric acid as a catalyst.I After esteriiication, the catalyst and the rosin acids are neutralized with the required amount of a 50% Water solution of caustic soda.

The mixture is now heated and the free methyl alcohol and water distilled off. The residue is .ject to economical recovery. It will also be noted then treated with acetone. which dissolves a certain sodium resinate, the fatty acid esters, and the unsaponiflnbles. Only the major portion of the light sodium abietate remains undissolved. The said undissolved type; or light sodium abietate, is then removed, as by filtration and washed with acetone.

All the acetone washin'gs are then combined with the filtrate and then a low boiling hydrocarbon solvent, such as hexane, is added to ,the whole solution and thoroughly mixed. Water is added to this Lsolution until two layers form. `Since the acetone and the remaining sodium resinate are more soluble in water, they will readily separate, as a lower layer, from the hydrocarbon solution of the fatty acid esters, pitch and unsaponifiables. The two layers are then separated by decantation and the acetone-water layer is heated to distill off the acetone, leaving a water solution of the second type or dark sodium resinate.

The hydrocarbon solution of fatty acid esters, pitch and unsaponiiiablesis now heated to distill off the hexane. The residue is then dissolved in anhydrous methyl alcohol and' solid caustic soda ilakes are added in large enough proportions to completely'saponify the fatty acid esters. This mixture is heated for about two hours and then the alcohol is distilled off. The residue is again treated with anhydrous acetone which dissolves only the pitch and unsaponifiables (sterols included).

The residue of sodium salts of fatty acids is alcohol we may use ethyl,

tion, whereupon alcoholsand 'hydrocarbons are of ters and dark theacetone vapors recovered, or they may be' dissolved in water, the ketone stripped therefrom, and :iwdrolfyzed 'to uecoverthe fatty 'acids The filtrate/and .washings are then heated 'and .the acetone distilled off until the residue/in the still consists of approximately 1 part unsaponifiables and 1 part acetone. .This solution .is chilled to crystallize the sterols from the :solution.

The sterol crystals are then removed, 1as by filtration, and the filtrate is heated to distill off the remaining acetone. The residue consists of pitch and possibly some higher alcohols and hydrocarbons.

The light sodium abietate obtained from the first separation may now be hydrolyzed andthe liberated light abietic acid purified -by crystallization 4from a hydrocarbon. We have found that if the light ysodium abietate obtained from .the r-iirst 'separation is -re-crystallized from anhydrous methyl alcohol, .pure white crystals of sodium abietate can-be obtained. `If the purified` sodium abietateis then hydrolyzed with a mineral acid, andthe product is crystallized .from a hydrocarbon, is obtained.

The -dark sodium resinate obtained from the xsecond separation may be separated from the Water :by evaporation -or l-salted -out of the water solution .and-dried as sodium lresinate, or it may 'be hydrolyzed .and a dark brown rosin acid obtained. AThe sodium salts ofthe fatty acids may -be hydrolyzed-and a substantially rosin-free fatty acid may be. obtained, the color :of which is :lighter than commercial crude oleic acid.

The sterols may be purified by recrystallizapure white-crystals are obtained. pitch and possibly some higher a color similar rJlhe residual .to the fatty .acids obtained.

Although yneutralization of the sulphuric acid and the rosin acids may be :effected lwith a water solution of caustic soda, we yprefer to employ an cohol -solvent for the caustic soda to enable `more ready removal ofthe solvent =preparatory `to use of the ketone.

In the operation of our process the starting ,material may :be yfirst freed of pitch and sterols .andfany oxidized rosin, so that suchstarting -ma- .terial maybe termed mixed acids, yi. .e., a mixture 4containing chieiiy the .Water insoluble fatty .'aclids and light and vdark rosin acids, found in tall oi These "mixed acids are esterifled by anhydrous Vmethanol inthe presence of an lesterifying catalyst such as sulphuric acid, as indicated in the annexed drawing the treatment 4of tall oil. In fact, the ,procedure is identical with that .employed in the treatment of tall oil with the exception that a number of the later steps are omitted. By such .ester-ification the fatty acids are `converted 'tocertain alcohol esters, but the two types of rosin acids remain unreacted.

The mixture of alcohol esters .and rosin acids is subjected'fto `the action .of caustic soda followed by :stripping 01T methanol. A n anhydrous ketone such as .acetone 4then is added, whereby the light sodium abietate is precipitated and may be removed, as by filtration.

.The resulting solution contains fatty .acidessodium resinate. 'The acetone is pure white crystalline -abieticacidv Iwhich relates primarily -tohydrolyzed mixture.

stripped from the solution and the latter is run ane stripped from the layer of fatty acid esters ifor recovery of the latter, and water evaporated .from the .dark .sodium resinate.

The .dark sodium resinate if desired, may be for -the recovery of dark rosin acid.

If desired, theifatty acid esters may be saponiiied to produce fatty acid sodium salts and these in 'turn may be hydrolyzed for the production and `recovery lof substantially pure fatty acids.

vlts-exzamples Example I Tall oil with the following analysis .was .used asa raw material for this experiment:

Rosin No.=73 .Rosin acid=39;25% Saponifica- Unsaponition No.=1.66 able=18.00%

"202 -parts by weight of tall oil was .added to parts by Weight of anhydrous methanol and 27 partsby weight of methyl sulphuricacid. The mixture was refluxed .for four hours. At the end ofthe reflux period, 13.5,parts by weight of caustic soda was added to saponify Ithe rosin acids and neutralize the sulphuric acid catalyst.

The free methanol was then distilled out of the 'The residue was treated with two portions each of 500 parts by weight of 99.9% acetone and filtered. The lter cake was dried and hydrolyzed with mineralacid and 50 parts by weight of abietic acid were recovered. The filtrate was added to 750 parts by weightof hexane, with a 'boiling range of 60-70" C. 500 parts by weight of water were then added; the mixture was slowly agitated and allowed to stand. In about 20 minutes, two layers were formed, the lower layer con- :taining acetone, water, and the sodium salts of rosin acids along with a small amount of fatty esters. The upper layer consisted of .hexane, lfatty esters, pitch, and unsaponiiiables.

The lower layer was distilled to recover the acetone. The residual' solution of water and 'sodium resinate `was then hydrolyzed and another portion of dark rosin acids was recovered amounting to 35 parts .by weight.

'I'he upper layer was now distilled to recover the hexane. The residue was saponified by heating lfortwo .hours with alcoholic solution `of .caustic soda v(15 parts Aby weight of caustic soda in 160 parts .by weightnf methanol). The alcoholic solution of sodium salts of .fatty acid 'was then distilled .to recover .the alcohol. The residue was treated with two portions, each of 400 parts by weight,.of.acetone and filtered after leach acetone treatment. The .iilter cake of sodium salts 'of fatty acids`was then vdissolved in water, .heated to 'recover the acetone, and then hydrolyzed with a small excess of mineral acid. Hexane was added to pick up the fatty acids, the mixture being settled to .form two layers, `the top layer being a hexanesolutionof fatty acids, which was separated and strippedofsol-vent. Ellie fatty acid ',ecover the acetone. .38 parts by weight of un- /gaponifiablea pitch and sterols, and possibly other unsaponiables, were recovered in the residue.

The sterols may first be separated from the acetone solutiomby chilling the same to crystallize the sterols, the crystals being removed, asby illtration, their recovery being 4.5 Parts by weight. The pitch recovery, including any other unsaponlilables, was 33.5 parts by weight.

assuma to the ease of polymerization. Also no separation vof the diiferent typesv of rosin acids is accom pli'shed, since in the said process they are removed as a mixture. The fatty acid recovered r by this said process was rather dark and of poor our process.

quality. All of these diiilculties'are avoided by It will be understood that while we prefer the use of sodium hydroxide as the saponifying agent for the rosin acids, other saponlfying agents recand approximately two'years old was added to v80 C parts by weight o1'y anhydrous methanol and 6 parts by weight of concentrated sulphuric acid. The procedure in this example was identical with that employed in Example I.

The first rosin acid `fraction recovered amounting to 50 parts by weight was dissolved in 15b parts by weight of hexane and allowed to cool and crystallize. The rosin acid crystals obtained had a melting point of 192 C. and an. apparent molecular weight of 406 as determined from the acid number. Y The second fraction of rosin acid recovered amounted to 36 parts by weight, giving a total of 86 partsA by weight of rosin acid recovered. The fatty esters recovered weighed .116 parts by weight 'of rosin acid recovered. The fatty esters recoyered weighed 116 parte by weight, which upon saponioation, yielded 9d parts bylweight di fatty acids. The fatty acid had a color resembling crude commercial oleic acids, sterols and pitch, which comprises selecl ognized asv equivalents may be substituted.

Having described our invention, what we claim and desire to. secure by Letters Patent is as follows; v

l. In la process of separating and .recovering constituents of tall oil and other mixtures containing chiely water-insoluble fatty acids, rosin tively esterifying the fatty acids only with a monohydric alcohol in the presence of an esterifying catalyst, saponifying the rosin acids with sodium hydroxide and stripping od the excess alcohol,

the step oradding a substantially anhydrous aliphatic ketone selected from the group consisting of acetone, methylethyl ketone and diethyl ke- 'tone to the mixture of esterifled and saponiiled 'constituents whereby the constituents are disacid. A total of 20 parts by weightof unsaponiilables werezalso recovered.

Our method overcomes great difilculties found with other methods which have heretofore attempted the separation of fatty acids and rosin acids from Itall oil and employing the principle oi esterii'ying the fatty acids without esterincation of the-rosin acids. For example, it has been heretofore-proposed (United States Patent No.

l,736,802) to effect separation by esteriiyne the' vfatty acids of the mixture with alcohol (which.

would logically be considered ethyl alcohol), using sulphuric acid as the catalyst, and after esterification vmeutralizing the free rosin and mineral acids with a water solution of caustic soda. lThe resulting mixture of sodium resinates and esteriiled fatty acids was treated with a hydrocarbon and water in an attempt to dissolve the esterified fatty acids and unsaponifiables and wash out the sodium resinates with Water. Such a method, however, forms a layer containing the esteried fatty acids in stubborn emulsion with the Water solution of sodium resinates. This emulsion is so dit stubborn that it is commercially impossibleto obtain goed separation.

.d second proposed method, based on the selective esterirication principle (.United States Patent No. 2,l6d,3l2) is similar to thatjust described but employs iurfural in conjunction with a hydrocar bon in. 'an attempt to separate the fatty acid esters.- andsodium resinates. The resulting mixture is stirred and water is added to separate the mixture into two layers. 'The lower layer con... siste oi. sodium resinate, iurfural and water, while the upper layer consists of a hydrocarbon solution of fatty acid esters and some unsaponiiiables.

ln the subsequent treatment of these layers stub.- born emulsions are formed, and, furthermore, the

solved with the exception of light sodium abletate, and removing the light sodium abietate.

2. In a process of separating and recoveringl constituents of tall oil and other mixtures containing chiey water-insolubleA fatty acids, rosin acids, sterols and pitch, which comprises selec.

. tively esterifying the fatty acids only with a monohydric alcohol in the presence of an esterii'ying catalyst, saponifying the rosin acids with sodium hydroxide andlstripping oil? the Vexcess alcohol, the steps of adding a substantially anhydrous aliphatic ketone selected from the group consisting of acetone, methylethyl ketone and diethyl ketone to the mixture of vesterified and saponified constituents, whereby the constituents are dissolved with the exception of light sodium abietate, removing the light sodium abietate, stripping ketone from the remaining solution, adding water and a lower boiling hydrocarbon selected from the group consisting of hexane, gasoline, and kerosene and settling to form two layers, the upper layer being a hydrocarbon solution'oi fatty acid esters, pitch and sterols, and the lowerlayer being dark sodiuni'resinate in Water solution, sepa arating the layers and evaporating water from the water layer for the recovery of darlrsodium resinate.

3. n a process of separating and recovering constituents of tall oil and other mixtures. containing chieiiy water-insoluble fatty acids, rosin acids, sterols and pitch, which comprises selectively esterifying the fatty acids only with a monohydric alcohol in the presence oi' an esterifying catalyst, saponifyingthe rosin acids with .sodium hydroxide and stripping ofi the excess alcohol, the steps of adding a substantially anhydrous aliphatic ketone selected from the group consisting of acetone, methylethyl ketone and diethyl. ketone to the mixture of esteried and saponiiied constituents, whereby the constituents are dissolved with the exception of lightsodiuin abietate, removing the light sodium abietate, 'stripping iretone from the remaining solution, adding water and a tower boiling hydrocarbon selected from the group consisting of hexane, gasoline, and hercomplete recovery of furfurai is very dimcult due and stencils, and the lower layer 'being clark sodium resinate in water solution. separating the layers, evaporaiing .the hydrocarbon trom the upper layer, saponifying said layer with sodium hydroxide tu the presence of a monohydric alcohol .similiar to that initially employed, stripping 'oif the alcohol, mixing the resulting salts of fatty acids, pitch and sterols with anhydrous aliphatic ketone :to precipitate the sodium salts .of fatty acids, and removing the said sodium salts,

4. .In a :process lof separating and recovering constituents =of tall oil and other mixtures containing chiefly water-insoluble .fatty acids, rosin acids, sterols a'nd pitch, which .comprises selectively esterifying the fatty acids only with a monohydnic alcohol in the presence of an `esterifying catalyst, saponirfying the rosin acids with sodium hydroxide'and :stripping oi the excess alcohol,

assayed.

alcohol, .subjecting the mixture to the solvent aotion of a substantially anhydrous aliphatic ketone selected from the group consisting -of .acetone, 4methylethyl ketone and diethyl ketone, whereby vthe light sodium abietate remains `undissolved, removing the vlight sodrum abietate, stripping the ketone from the remaining solution, then adding water and a low boiling hydrocarbon selected from the group consisting of hexne. gasoline, and kerosene to the mixture and settling to form two layers, the upper layer consisting of 'a hydrocarbon solution of monohydric fatty acid esters, and the lower layer consisting of sodium resinate in water solution, separating the layers, and evaporating the hydrocarbon from said upper layer to recover the fatty acid esters.

7. A process of separating and recovering 'con- -sutuents or tauouconsisung of mixture of waterthe steps of adding a substantially anhydrous =ali Iinsoluble fatty lacids and rosin acids, which comprises adding to said mixture a monohydric 'aloohol in the presence of an -esterifying .catalyst and a lower .boiling hydrocarbon selected from the group consisting of hexane, gasoline, and kerosene to .form two layers, the upper layer being a hydrocarbon solution of fatty acid esters, pitch andsterols, and the lower layer being dark sodium resinate in water solution, separating the layers, evaporating the .hydrocarbon .from the upper layer., saponifying said layer with Asodium hydroxide in the presence of a vmonohydric alcoho1 similar to that .initially employed, .stripping olf the alcohol, mixing the resulting sodium salts of datty acids, pitch `and sterols with anhydrous aliphatic .ketone to .precipitate the sodium salts of fatty acids, removing the said sodium salts, subjecting the ketone solution-of pitch and sterols to chilling and crystallization di the sterols, removing the crystalline sterols, and evaporatng the ketone to recover the pitch.

5. .A .process in accordance with claim l., in which the .ketone .is substantially anhydrous acetone.

6. A process oi' separating and recovering constituents of tall oil consisting of mixtures oi.' water-.insoluble fatty acids and rosin acids, which comprises adding to said mixture a monohydric alcohol .in the `presence of an esterifying catalyst and thereby selectively esterifying the fatty acids only, adding .sodium hydroxide and thereby saponifying the rosin acids, stripping oi the excess and thereby selectivelyesteriiying the fatty acids only, adding sodium hydroxide and thereby sapohifying the rosin acids, stripping -off the excess alcohol, subjecting 'the mixture to the solvent aotion of a substantially anhydrous aliphatic ire` tone selected from the group vconsisting xof acetone, methylethyl ketone and diethyl ketone, whereby the light sodium abietate remains undissolved, removing the light sodium abietate, stripping the ketone from the remaining solution, then adding water and a low boiling hydrocarbon selected from the group consisting oi.' hexane, gasoline, and kerosene to the mixture and settling .to lform two layers, the upper layer consisting of -a hydrocarbon solution of monohydriciat- `ty acid esters, and the lower layer consisting oi' sodi-um resinate in water solution, separa/ting vthe layers, evaporating the hydrocarbon from .the upper layer.; saponifying the last named llayer with sodium hydroxide in the presence of .a monohydric alcohol similar .to that .initially employed, evaporatingthe alcohol, mixing the residue with substantially anhydrous aliphatic ketone whereby the sodium salts of fatty acids are precipitated, and removing the said .precipitated sodium salts of fatty acids.

.8. A process in accordance with claim .1, in which the light sodium abietate is mixed with hot anhydrous .methyl alcohol followed -by chilling the solution, thereby crystallizing pure white crystals of sodium abietate.

JOSEPH JOHN LOVAS. PAUL F. 'BRUINS 

